Many bosses are really hard and have racked up a dozen kills per player.
What boss has the community labeled as a pushover that you've died an embarrassing number of times to?
Crystal Sage from DS3 has killed me at least 8 times every playthrough, but every forum I've visited has made them seem easy.
Deacons of the Deep in dark souls 3. I was running a light dex build at the time (I think using a rapier?) and it was a bit of a nightmare.
The boss is supposed to be piss easy but if you don't have any sweeping attacks it quickly becomes unmanageable becauss you can't kill them fast enough and they keep spamming annoying spells.